Electromagnet.



0. W. COLEMAN. ELEGTROMAGNET.

APPLICATION FILED MAY 21, 1909.

1,015,992, Patented Jan.30, 1912.

.l @Jvitmeoaeo: wamveutoz $513k aHoM w 4 z UNITED STATES PATENT OFFICE.

CLARENCE W. COLEMAN, 0E WESTFIELD, NEW JERSEY, ASSIGNOR TO THE HALL SIGNAL COMPANY, A CORPORATION OF MAINE.-

ELECTROMAGNET.

Specification of Letters Batent.

Patented Jan. 30, 1912.

- Application filed Kay 21, 1909. Serial No. 497448.

To all whom it may concern:

Be it known that I, CLARENCE W. COLE- MAN, a citizen of the United States, and a resident of VVestfield, Union county, State of New Jersey, have invented certain newmagnetic engaging surfaces, and with a non-magnetic insert 1n one of said members, so that a magnetic path is obtalned with a so-called magnetic break or air gap which will remain constant regardless of the wearing away of the engaging surfacesof the relatively movable members. By thus providing such a magnet with a non-magnetic insert, I am enabled to obtain the slow release ofthe magnet armature which is essential for certain magnets used in signaling systems in order to prevent the release of the armature during sudden reversals of current, and at the same time insure the proper release of the armature at predetermined current values and avoid the danger of sticking.

My invention is especially useful in magnets such as are used in railway signal relays, electro-magnetic clutches and other electrical apparatus in which it is required that the magnet attract its armature at a given current strength, such, 'for instance, as magnets which have a limited source of current and must be so wound that they will not operate in response to a slight leakage of current in their circuit.

I have shown my invention as embodied in an electro-magnetic clutch arranged in connection with signal operating mechanism and comprising a core and an armature with magnetic engaging surfaces and with a non-magnetic insert in said core or armature, for maintaining a constant magnetic air gap in said circuit. The function of a non-magnetic insert in any magnetic circuit is to introduce such a magnetic reluctance in the circuit as will insure the separation of the armature from its core to prevent sticking either upon the opening of the circuit to the magnetic coils or upon a predetermined decrease of current in said coils.

When it is desired that the armature should be released only upon the opening of the energizing circuit it is important that the insert should not beat the engaging surfaces, since for an eflicient magnet the insert is necessarily thin, and if placed at the engaging surfaces it will be quickly worn awayby the constant hammer blows received.

If the use of the magnet requires that its armature should be released at a predetermined current in the energizing circuit and before the circuit is opened then it is highly importantfor accurate and eflicient operation that the non-magnetic insert will not be subjected to the wear that the engaging surfaces must receive; since the magnetic reluctance of the relatively thin insert forms a large percentage of the total reluctance of the circuit, and any appreciable wear on, or irregularities in, the surfaces will greatly affect the current value at which the armature is released.

My invention will be best understood by the following description taken in connection with the accompanying drawings, in

"which,

Figure 1 1s a plan view partly in section Referring to the drawings, Fig. l; 1 is a magnet core preferably of soft iron having the usual energizing coils 2, and a closed coil 3 on each leg for retarding the magnetic changes in the core, as is well known in the art. 4 is a soft iron armature having magnetic engaging surfaces 5 with interposed sheets of thin non-magnetic material 6 preferably copper, riveted thereto at each end by copper rivets 7 The engaging surfaces of the magnet and armature being of magnetic material, can be almost entirelyworn away, without affecting the value of the exciting current at which the armature will be released, since the reluctance of this relatively short length of magnetic circuit is negligible as compared with the entire reluctance of the circuit. The comparatively thin non-magnetic insert which forms a large part of the total reluctance of the circuit and which if at all worn would materially affect the value of the exciting ourrent at which. the armature is restored, is placed where it is fully protected from any wear; so that the current value at which the armature will be released will not be afi'ected by the wearing away of the engag ing surfaces.

In Fig. 2, I have shown the magnet 1 con- I nected up toa track circuit with its armature- 4 mounted on a swinging bar 8 whlch laterally controls the clutch mechanism of a railway signal. A semaphore (not shown) is secured bya rod to a set ofpivoted links 10, which are adapted to be moved by a plurality of bars, one of which is shown at 11. Each bar is provided with a pivoted latch 1.2 and a pivoted lever 13 carrying a roller 14 at its lower end and having a shoulder 15 formed at its upper end. Each bar is also provided with a bracket 16 upon which is pivoted an arm 17 carrying adogv 18 for engaging the shoulder 15. Pivoted adjacent the bar 1 1 is a gear wheel 19 driven by a suitable electric motor 20 and having two ro'jecting r'ollers 21 for engaging the arm 1 7. p

A more complete description of the signal operating mechanism and clutch is thought to be unnecessary here since the same is --fully shown and described in my United States Patent, No. 806,238, patented December 5th, 1905.

Assuming that a car is on the block with -the signal at danger and the apparatus in the position shown; the operation is as follows: When the car passes oil of the block the circuit to the motor 20 is closed in any well known manner and the magnet 1 is I energized to attract its armature and hold bar 8 from being swung upward. As the motor starts up it drives the gear wheel 19 causing one of the rollers 21 to engage arm 17 and move dog 18 into engagement with shoulder 15 on the lever 13, thus throwing the roller 14 against bar 8, which prevents the lever 13 from swinging out of the path of the dog, so that thebar 11 is raised through engagement with the dog, as the wheel continuesto rotate,-thus moving links 10 for clearing the signal. When the bar 11 has been raised to its upward position, latch 12 is in position to engage a shoulder 22 on the swinging bar '8, so that as the roller 21 passes from underneath arm 17,

. the bar 11 is supported in its raised position swing upwardwhen engaged by roller 14, it

will be impossible to clear the signal since the engagement of dog 18 with shoulder 15 will tilt the lever 13 on its pivot allowing the arm 17 carrying the dog to swing upward past the shoulder as the wheel 19 is rotated. It will be seen that with such a construction it is important that thethin non-magnetic inserts should be protected from the serious hammering that the engaging surfaces of the core and armature are subjected to, or else they would frequently have to be renewed.

While I have shown and described with particularity my invention as applied to a magnet controlling clutch mechanism, and so connected that the armature is only released when the exciting circuit is opened; it is obvious that it may readily be used for many other purposes and adapted to be connected in circuit with a varying exciting current so that it will release its armature at (it predetermined change in said current; an

What I claim as new and desire to secure by Letters Pate'nt, is: I

1. The combination of a slow'release magnet having a magnetic engaging surface, an

armature forsaid magnet also havmg a magnetic engaging surface and a non-magnetic insert intermediate the extremities of the magnetic path of said armature, whereby the wearing of the engaging surface will not affect-said insert. p

2. The combination of a core and its armature hav'ing magnetic engaging surface, a coil for energizing said core and armature, a'second coil upon one of the parts closed-upon itself for retarding the magnetic changes'in said parts and a non-magnetic insert in one of said parts intermediate its engaging surfaces.

In testimony 'whereof,'I have signed name to this specification, in the presence of t-wo subscribing witnesses.

'Witnesses ANNA DALY, EDWIN SEGER. 

